effect of canopy shading on relative primary productivity of periphyton in Water Conservation Area 2-A, Everglades

Differences in relative primary productivity of periphyton were determined for three light regimes: open slough (control), sawgrass canopy, and cattail canopy. The center of Water Conservation Area 2-A, Everglades was chosen as the study site because it is relatively unaffected by nutrient runoff. Periphyton productivity was determined by the light and dark bottle method, and biomass was recorded as ash-free dry weight. Statistically significant correlations were found between periphyton biomass and water temperature and between organic content and water temperature. Mean photosynthetically active radiation reaching the surface of the water under sawgrass and cattail canopy was 45% $\pm$ 3% and 11% $\pm$ 1% respectively. Relative primary productivity of periphyton was lower under cattail canopy than under sawgrass canopy due to increased shading of cattail. This reduction of periphyton biomass and primary productivity can be considered an indirect effect of nutrient enrichment from the Everglades Agricultural Area.